Biological communities

Chapter 17Ecology Unit Biological communities

What happens in communities? • We all know that ecology is the study of interactions among species and/or between species and their respected environments. • We are now going to learn about some of those interactions.

Co-evolution • Because organisms are constantly interacting, wouldn’t it make sense that they would adapt to each other as well? • co-evolution is the back-and-forth evolutionary adjustments (adaptations) between interacting members of a community • Example: plants and their pollinators

Co-evolution happens through many interactions • There are interactions in which both of the species benefit • This is called mutualism, and is a +/+ interaction • Examples of mutualism are plants and pollinators, or ants and acacia trees

Co-evolution happens through many interactions • Predators and prey co-evolve as well • In predation, one organism is killing another for food • Predation is a +/- interaction, in which one organism benefits while the other suffers • Prey evolve to better avoid predators and predators evolve to better catch prey

Co-evolution happens through many interactions • In their own rights, parasites can be considered predators because they use other organisms as a food source • However, parasites generally don’t kill their hosts • Parasitism is also a +/- relationship because the parasite benefits while the organism it’s residing in (the “host”) suffers • Hosts evolve to be less susceptible to parasites, while the parasites evolve to either work around the host’s susceptibility or to be able to survive in a variety of hosts

Co-evolution happens through many interactions • There are symbioses in which only one of the two species are affected • In this symbiosis, called commensalism, one of the species is benefitted while the other isn’t affected positively or negatively +/0 • Example of this is clown fish in anemones

Co-evolution happens through many interactions • Herbivores may not be seen as predators, but to plants they most certainly are • Plants have different methods for defense against herbivores, both physical and chemical • On the other hand, as plants gain these defenses (such as secondary compounds which chemically ward off herbivores), the herbivores are gaining resistance to these defenses

Some species are necessary in an ecosystem • There are some species that are so important that their population being present is vital for the survival of an ecosystem • These are called keystone species • Changes in the populations of these species can cause huge changes in the structure of a community • Ex: starfish! They keep the population of mussels under control so they don’t take over the ecosystem.

Climate impacts communities • How do you think climate impacts communities?

Climate impacts communities • Different organisms fare better in different climates • Climate is the average year-to-year conditions of temperature and precipitation in an area over a long period of time • Examples of organisms that are seasonal? That live in different places at different points of the year to remain in a similar climate?

Biomes are classified partially by climate • So, where do scientists use the information about biotic and abiotic factors of an ecosystem? • One way this information is used is to classify the different biomes • Biomes are described in terms of abiotic factors such as climate and soil type, as well as the biotic factors of what plants and animals live there.

There are lots of biomes • Tropical rain forests- abiotic: hot and wet year-round with thin, nutrient-poor soil subject to erosionbiotic- many levels of vegetation fighting for sunlight; many species of animals (many with strong abilities of camoflauge) • Located in Central and South America, Africa, and Asia

There are lots of biomes • Tropical dry forests-abiotic: warm year round; alternating wet and dry seasons; rich soil-biotic: leaf shedding trees, plants with thick cuticles to reduce water loss; animals that have long periods of inactivity during the dry season • Found in parts of Mexico, India, South America, and Southeast Asia

Other Examples of Biomes • The rest of the biomes include savannas, deserts, temperate grasslands, temperate woodlands, temperate forests, coniferous forests, boreal forests, and tundra • Each experiences different climates, and therefore hold different types of life (some seasonal, some year round) • Florida’s biome?

Florida’s biome(s) • Florida is a majority temperate forest with some tropical grassland/savanna • Which part of Florida would comprise the tropical grassland?

Florida’s biome(s) • Temperate Forest-abiotic: cold to moderate winters; warm summers; year-round precipitation;fertile soils-biotic: trees that drop their leaves to go dormant in winter; animals that can cope with changing weather, hibernate, or migrate • Savanna/Tropical Grassland-abiotic: warm; seasonal rainfall; compact soils; frequent fires set by lightning-biotic: plants with waxy cuticles to prevent water loss; animals who move when water is low

Organisms have native habitats • Every living organism has a habitat/location that they are native to • When these organisms enter an ecosystem that they are not native to, they are considered non-native to that environment • These organisms can enter the ecosystem in multiple ways, such as?

Organisms have native habitats • Non-native species enter the ecosystems in more than one way • Some enter the ecosystem by accident (such as through importing/exporting goods) • Some are deliberately introduced by humans for reasons such as controlling other populations

Organisms have native habitats • Some of these species that are introduced to new ecosystems do not hurt it • However, some are extremely disruptive to the ecosystem • Those species that are considered disruptive to the ecosystem that they have been introduced to are considered invasive species

Invasive species hurt ecosystems • Invasive species can do many things to hurt the ecosystem1. take food from the native species2. mate with the native species, making hybrid species3. take habitat from native species • Some species that we may have seen around us all of our lives may actually be invasive • Ex: Iguanas in Florida

Ecosystems aren’t just on land • Ecosystems are present in the water as well • Ponds, lakes, rivers, oceans, etc. all contain ecosystems

Ecosystems aren’t just on land • Bodies of water have different levels, each with defining characteristics • The photic zone of a body of water is the sunlit region near the surface-what process can occur?-phytoplankton (algae) and zooplankton (animals that eat phytoplankton) live at this level • The aphotic zone is dark; underneath photic zone-photosynthesis cannot occur-much aquatic life lives in this zone

Ecosystems aren’t just on land • Oceans are a great place to find a diversity of life at many levels • Very deep in the ocean, where we have only recently been able to travel, there have been many interesting (often weird) fish and invertebrates discovered • These animals are accustomed to the deep, cold, high pressure conditions of the deep ocean

Ecosystems aren’t just on land • In freshwater bodies (lakes and ponds), there are also zones of where animals live-the littoral zone is the shallow zone near the shore that holds aquatic plants, predatory insects, amphibians, and small fish-the limnetic zone is farther away from the shore, close to the surface and holds algae, zooplankton, and fish-the profundal zone (not all lakes/ponds have these) is deep water where bacteria and wormlike organisms decay debris and recycle nutrients

Examples of the bizzare

Self Check • Think about the environment. What do you know about the environment? What have you learned and/or heard about the environment in recent years? Who do you think should be responsible for taking care of the environment? Are the government and environmental agencies doing enough? Write your answer in a paragraph.

Biological communities